Planned research will proceed along 2 main lines: 1. Microtubule rearrangement and chromosome movement. 2. Spindle models in lysed cells. 1. The results obtained in the course of the present investigations in our experimental systems (newt lung cultures and Haemanthus endosperm) point to a general principle in chromosome movements: "The chromosome movements occur only during the rearrangement of microtubules from a regular (more or less parallel) to an irregular or irregular to regular array. No movements occur when microtubules are either parallel or in total irregular disarray." Changes of microtubule arrangement result from their active lateral interaction (zipping) combined withcontrolled assembly-disassembly. Further studies on the effect of shifting the equilibrium assembly-disassembly of microtubules toward assembly or disassembly are planned (studies on the combined actions of glycols, temperature, etc.). Local disassembly of microtubules in large areas of the spindle for various periods of time should be especially instructive. 2. No success was obtained in repeating experiments done in other laboratories claiming continuation of chromosome movements in lysed cells. Our data point out that the beat frequency of cilia is a promising indicator of the suitability of the lysing media (work on isolated lung cilia and ciliated cells in tissue cultures of the newt lung). Further experiments are aimed at obtaining media which will support chromosome movements after cell lysis.